No one gets off the hook on this one -- from governments to schools, corporations to nonprofits, all the way down to families sitting around their dinner table."

VOA: special.2010.06.07

You hook one end of the spring to a wall and you pull it from rest by some amount and you attach the one kilogram mass to it.

你把弹簧的一端固定在墙上,然后拉伸一段距离,接着你把 1 千克物体固定在上面

耶鲁公开课 - 基础物理课程节选